非完整系统的Mei对称性直接导致的另一种守恒量

研究了非完整系统的Mei对称性直接导致的另一种守恒量,给出了这种守恒量的函数表达式和导致这种守恒量的条件方程.利用该方法比以往更易找到守恒量,最后举例说明了新结果的应用.     

时间尺度上非完整系统的Noether准对称性与守恒量

提出并研究时间尺度上非完整系统的Noether准对称性与守恒量.首先,将时间尺度上非完整系统的运动微分方程化为时间尺度上一般完整系统的Lagrange方程,在Lagrange框架下建立时间尺度上Noether定理,给出时间尺度上Noether守恒量;其次将时间尺度上非完整系统的运动微分方程化为时间尺度上相空间中一般完整系统的Hamilton方程,在Hamilton框架下建立时间尺度上Noether定理,给出时间尺度上Noether守恒量;再次,将时间尺度上非完整系统的运动微分方程化为时间尺度上广义Birkhoff方程,在Birkhoff框架下依据时间尺度上Noether准对称性的定义,建立时间尺度上Noether定理和广义Noether等式,给出时间尺度上Noether守恒量.最后,举例说明结果的应用.     

Lagrange系统的Noether-Lie对称性

研究了Lagrange力学系统的一种新对称性:Noether-Lie对称性及其守恒量.给出了Lagrange系统的Noether-Lie对称性的定义和判据,提出Lagrange系统的Noether-Lie对称性导致的Noether守恒量和Hojman守恒量.最后给出一个例子说明结果的应用.     

Vacco动力系统的Mei-Lie对称性

研究Vacco动力系统的一种新对称性:Mei-Lie对称性及其守恒量.给出Vacco动力系统的Mei-Lie对称性的定义和判据,提出受Vacco约束力学系统的Mei-Lie对称性导致的Mei守恒量和广义Hojman守恒量.最后给出一个例子说明结果的应用.     

广义Birkhoff系统的对称性与守恒量（英文）

研究了广义Birkhoff系统的3种对称性及其相应的守恒量.首先,基于Pfaffian作用量在无限小变换下的不变性,建立了广义Birkhoff系统的Noether理论;其次,基于微分方程在无限小变换下的不变性,建立了广义Birkhoff系统的Lie对称性的定义和判据,给出了由系统的Lie对称性直接导致的Hojman守恒量;最后,基于力学系统运动微分方程中出现的动力学函数在经历无限小变换后仍然满足原来方程的一种不变性,建立了广义Birkhoff系统的Mei对称性的定义和判据,给出了由系统的Mei对称性直接导致的Mei守恒量.举例说明了结果的应用.     

运用守恒思想解题

所谓守恒思想,就是抓住题中的守恒量(不变量)解题,在这类问题中至少有一个量是守恒的。守恒的类型有以下几种:明守恒、暗守恒和总量守恒。一、明守恒所谓明守恒,就是通过已知条件可直接求出守恒量(不变量),可根据这个守恒量解题。     

概率流密度矢量(J→)是方形势垒穿透中之守恒量

本文证明,在一维方形势垒贯穿中,概率流密度矢量J=Jex是一个守恒量.     

时间尺度上Hamilton系统的两类Mei对称性及其Mei守恒量

研究时间尺度上Hamilton系统的两类Mei对称性及由Mei对称性导致的守恒量.给出Hamilton系统的第一类Mei对称性定义和判据方程,引入时间尺度上的谐调函数,得出系统Mei对称性直接导致的广义Mei守恒量的条件和形式,同时,给出该系统在时间尺度上的第二类Mei对称性的定义及判据,进而推出其直接导致的Mei守恒量.并分别举例说明结果.     

完整约束力学系统的Noether对称性与Noether守恒量

研究广义坐标下完整力学系统的Noether对称性的定义和判据,给出由Noether对称性导出的Noethor守恒量,举例说明结果的应用．     

完整系统Tzénoff方程的三种对称性及其直接导致的守恒量

研究了完整力学系统Tzénoff方程的三种对称性及其直接导致的守恒量,给出了导致这些守恒量的判据方程和守恒量的函数表达式,最后举例说明了研究结果的应用     

对称性与守恒律

本文从对称性入手，阐述了物理操作的对称性的实质即为守恒律，并从系统的机械能对坐标的平移、旋转及时间平移的对称性出发。推导出动量、角动量及机械能守恒律。同时进一步阐述了“对称性破缺”所包含的深远意义。     

质点组动量守恒的中的速度问题

利用动量守恒定律分析质点组问题时，必须注意质点组各质点速度的空间统一性和时间统一性。     

Creating Knowledge for Advocacy: The Discourse of Research at a Conservation Organization

In the field of conservation, the distinction between academic research and advocacy appears to be undergoing a shift as the number of PhD-level researchers at conservation advocacy organizations grows. Drawing on my case study of one researcher at a prominent conservation nongovernmental organization (NGO), I have shown how this shift is manifested in the communication of NGO research. My study includes a discourse analysis of this researcher's publications from the forums of both scholarship and advocacy including, as a representation of discourse in the latter forum, gray literature (reports, books, and other texts produced and distributed outside the channels of the academic and publishing industry). I have also drawn on my interviews with this researcher about her publications. My study highlights specific features typical of her rhetoric that result from her occupying a hybridized cultural and professional space where research and advocacy overlap.     

Creating Knowledge for Advocacy: The Discourse of Research at a Conservation Organization

In the field of conservation, the distinction between academic research and advocacy appears to be undergoing a shift as the number of PhD-level researchers at conservation advocacy organizations grows. Drawing on my case study of one researcher at a prominent conservation nongovernmental organization (NGO), I have shown how this shift is manifested in the communication of NGO research. My study includes a discourse analysis of this researcher's publications from the forums of both scholarship and advocacy including, as a representation of discourse in the latter forum, gray literature (reports, books, and other texts produced and distributed outside the channels of the academic and publishing industry). I have also drawn on my interviews with this researcher about her publications. My study highlights specific features typical of her rhetoric that result from her occupying a hybridized cultural and professional space where research and advocacy overlap.     

用对称性原理推导力学守恒定律

本文在宏观经典力学范畴内,利用对称性原理,从时间平移不变性推出机械能守恒定律,从空间平移不变性推出动量守恒定律,从空间旋转不变性推出角动量守恒定律。     

经典物理学中的时空对称性和守恒量

对经典力学中的矢量力学形式、分析力学中的微分形式和积分形式的时空对称性进行了分析,探讨了空间均匀性、空间各向同性和时间均匀性所对应的动量守恒、角动量守恒和能量守恒三个守恒量的物理规律,从而全面阐述了经典物理学中的时空对称性与守恒量的关系.     

The structure of imagery.

Children's drawings of objects about to be moved in space (anticipatory images) were studied in relation to their judgments about Euclidean spatial relations. Tasks assessing Euclidean geometric operations were administered to 102 girsl between the ages of 4 and 13 years. 5 operative levels resulted: (a) failure on all operations tasks, (b) success on conservation of length, (c) success on conservation and 1-dimensional measurement, (d) success on the latter 2 tasks plus measurement in 2 dimensions, and (e) success on the latter 3 tasks and coordination of internal and external reference frames. The same children performed on 6 imaginal tasks involving movements of objects. Results confirmed several theoretical expectations: (a) children who were unable to measure had difficulty imaging successive positions for 1-dimensional movement; (b) children who were unable to coordinate a point in space by reference to 2 axes were unable to draw states of movement correctly for 2-dimensional movement; (c) children's errors in drawing successive positions of moving objects were related to the structure of operations at the lower levels; and (d) the coordination of object positions over successive states was dependent on the ability to measure from an external frame. The results were interpreted as support for Piaget and Inhelder's theory of imagery development.     

解Maxwell--Dirac方程组的守恒差分格式

提出了一种解Maxwell—Dirac（MD）方程组的守恒数值格式．第一部分将Minkowski空间中一维MD方程组转化为只包含两个无量纲变量的模型．然后介绍时间分裂法的思想,并且将其应用到转化后的模型．第三部分对MD方程组分裂后的两部分分别应用有限差分方法求解．此数值格式在时间方向是一阶精度,在空间方向是二阶精度的,并且得到守恒性等性质．最后应用实例验证数值格式的精度及守恒性等性质．     

物理学中的守恒定律及其地位

从时间的均匀性可推得机械能守恒定律,从空间的均匀性和空间的各向同性可分别推出动量守恒定律和角动量守恒定律。如果没有时间对称性、就根本谈不上物理学。因此,守恒定律是物理学的基石,它与基本定 律和各种物理现象一层层地构成了整个物理大厦。     

一类带有弱阻尼的非线性Schrodinger方程组的爆破性质

研究一类带有弱阻尼的非线性Schrodinger方程组的初值问题,通过在Sobolev空间中定义能量空间,运用能量方法,建立质量、能量守恒律,利用能量函数,得到在满足一定初始条件下,该方程组的解在有限时间内爆破的性质．